ci: convert travis-ci to github actions for im6

.github/workflows/ci.yml

@@ -0,0 +1,33 @@
+name: Test
+
+on:
+  push:
+    tags:
+      - "*"
+    branches-ignore:
+      - 'exp_*'
+  pull_request:
+    branches-ignore:
+      - 'exp_*'
+
+jobs:
+  test:
+    name: Test ImageMagick6
+    runs-on: ubuntu-latest
+    environment: imagemagick6
+    env:
+      DOCKER_IMAGE: gographics/imagick.v2:im-${{ vars.IMAGEMAGICK6_VERSION }}
+    # We want to run on external PRs, but not on our own internal PRs as they'll be run
+    # by the push to the branch.
+    if: github.event_name == 'push' || github.event.pull_request.head.repo.full_name != github.repository
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: Test
+        run: |
+          docker run --rm \
+            -v $PWD:/go/projects/imagick \
+            -v $PWD/.cache/go-build:/root/.cache/go-build \
+            -v $PWD/.cache/go/pkg:/go/pkg \
+            "$DOCKER_IMAGE"

Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.13
+FROM golang:1.20
 
 # Ignore APT warnings about not having a TTY
 ENV DEBIAN_FRONTEND noninteractive

README.md

@@ -1,22 +1,23 @@
 # Go Imagick
 
-[![GoDoc](https://godoc.org/gopkg.in/gographics/imagick.v2/imagick?status.svg)](https://gopkg.in/gographics/imagick.v2/imagick) [![Travis Build Status](https://api.travis-ci.org/gographics/imagick.svg)](https://travis-ci.org/gographics/imagick)
+[![GoDoc](https://godoc.org/gopkg.in/gographics/imagick.v2/imagick?status.svg)](https://gopkg.in/gographics/imagick.v2/imagick)
+[![Build](https://github.com/gographics/imagick/workflows/Test/badge.svg)](https://github.com/gographics/imagick/actions?query=workflow%3A%22Test%22)
 
 Go Imagick is a Go bind to ImageMagick's MagickWand C API.
 
 We support two compatibility branches:
 
 ```
-master (tag v2.x.x): 6.9.1-7 <= ImageMagick <= 6.9.9-35
 im-7   (tag v3.x.x): 7.x     <= ImageMagick <= 7.x
+master (tag v2.x.x): 6.9.1-7 <= ImageMagick <= 6.9.9-35
 legacy (tag v1.x.x): 6.7.x   <= ImageMagick <= 6.8.9-10
 ```
 
 They map, respectively, through gopkg.in:
 
 ```
-gopkg.in/gographics/imagick.v2/imagick
 gopkg.in/gographics/imagick.v3/imagick
+gopkg.in/gographics/imagick.v2/imagick
 gopkg.in/gographics/imagick.v1/imagick
 ```